The present disclosure relates generally to control of airflow, and more particularly to systems and methods for supplying and controlling airflow into (defined herein as an air conditioning system) and within (defined herein as an air distribution system) a vehicle.
In at least some known aircraft, such as civilian passengers, civilian freighters or military derivatives, if an air conditioning system on the aircraft ceases to operate, fresh air is supplied into the aircraft from an ambient environment. More specifically, a hole is defined in the fuselage of the aircraft and ambient air enters the aircraft through the hole in order to maintain desirable air temperatures, carbon dioxide and other undesirable gas concentration levels. Further, during certain other conditions, the manifold and ducting of the air distribution system may become highly restricted due to shutdown of flow to certain compartments. The typical design compensation to overcome these conditions is to either design the air distribution system for operation at greatly increased pressures, and/or to operate the air conditioning system with greatly reduced airflow, neither of which are preferred modes of operation. Operating the air conditioning system at greatly increased pressure requires added weight in order to achieve sufficient duct strength and robust sealing on the manifold to prevent damage as a result of the over pressurization. The air conditioning system is limited to a minimum airflow rate which is governed by the ability of the system to adequately control incoming air temperatures and maintain the minimum rotational speed of high-energy rotating equipment such as air cycle machines which generally rely on air bearings. Accordingly, a system that efficiently provides fresh air into an aircraft in the event that an air conditioning system ceases to operate and/or during other non-preferable conditions, that also eliminates the need to design the air distribution system to operate at abnormally high pressures, and/or greatly reduced airflow rates, is desirable.